1. Field of the Invention
This invention relates to the manufacture of articles such as slide fasteners, and particularly to the manufacture of small polymer articles such as coupling elements for slide fasteners and their attachment to a support tape.
2. Description of the Prior Art
The prior art contains many methods and apparatus for manufacturing small articles such as slide fastener coupling elements including the manufacture of coupling elements from polymer resin and the attachment of such elements to support tapes.
In one method and apparatus, coupling elements are formed by injection molding or casting in cavities from a molten supply of thermoplastic. These cast elements may be molded directly on the edge of a tape, molded on connecting filaments to form trains which are subsequently attached to an edge of the tape by sewing or weaving, or molded individually and then subsequently crimped on the edge of a tape or subsequently crimped on a carrier filament and then attached to a tape.
Another method and apparatus for manufacturing coupling elements and slide fasteners includes forming spiraled or convoluted continuous polymer filaments which are configured to interlock with mating coupling elements. These continuous filament coupling elements may be made by coiling or convoluting a continuous straight filament, or the filament of convoluted form may be cut from a continuous plastic sheet. It is known to heat the plastic to help in the formation of the convolutions and deformations necessary to form filamentary type coupling elements.
Still another method and apparatus utilizes the coining or deformation of elements from plastic or metal filaments and the cutting of segments either before or after the coining and deforming to form individual elements. These elements may be sewn or attached by crimping to the edge of a tape or cord.
The use of ultrasonic energy to weld leg portions of continuous filament type coupling elements together or to the edge of a tape has been disclosed in the prior art. Also ultrasonic energy has been utilized for fusing coupling elements together to form bottom stops on slide fasteners as well as to simultaneously cut a continuous slide fastener chain into segments to form individual slide fasteners. Further slide fastener tapes have been channelized by ultrasonic energy. Ultrasonic energy has also been used to plasticize and mold top stops from severed portions of filamentary material onto tapes and top elements of slide fasteners.
The invention is summarized in a method of manufacturing coupling elements for a slide fastener, the steps including advancing a continuous filament of thermoplastic, severing segments of the filament, placing the severed segments of the filament into succeeding cavities in a periphery of a cavity wheel, plasticizing the severed segments of the filament, and molding the plasticized severed segments to at least partially formed coupling elements, the plasticizing and the molding being preformed situ in the cavities of the cavity wheel.
An object of the invention is to provide substantially new and improved techniques for producing and/or attaching small polymer articles such as coupling elements for slide fasteners.
Another object of the invention is to produce closer dimensional control of elements employed in slide fasteners.
It is still another object of the invention to reduce or eliminate the production of flash and the necessity of skiving operations to remove excessive plastic in the formation of coupling elements.
A further object of the invention is higher productivity in the manufacture of slide fastener elements.
Other objects, advantages, and features of the invention will be apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.